Give the structure of the principal product(s) when each of the following alcohols reacts with (1) Na₂Cr₂O₇/H₂SO₄, (2) PCC
c. 4-hydroxydecanal

Verified step by step guidance

1. Step 1: Understand the reagents and their roles. Sodium dichromate (Na₂Cr₂O₇) in the presence of sulfuric acid (H₂SO₄) is a strong oxidizing agent. It can oxidize primary alcohols to carboxylic acids and secondary alcohols to ketones. Pyridinium chlorochromate (PCC) is a milder oxidizing agent that oxidizes primary alcohols to aldehydes and secondary alcohols to ketones without further oxidation to carboxylic acids.
2. Step 2: Analyze the structure of 4-hydroxydecanal. It contains both an aldehyde (-CHO) group and a hydroxyl (-OH) group. The hydroxyl group is on the fourth carbon, and the aldehyde group is on the first carbon of the decanal chain.
3. Step 3: Predict the reaction with Na₂Cr₂O₇/H₂SO₄. The strong oxidizing agent will oxidize the primary alcohol (if present) to a carboxylic acid. However, in this case, the aldehyde group (-CHO) will be further oxidized to a carboxylic acid (-COOH). The hydroxyl group on the fourth carbon will remain unaffected as it is a secondary alcohol.
4. Step 4: Predict the reaction with PCC. PCC, being a milder oxidizing agent, will not oxidize the aldehyde group further. It will leave the aldehyde group intact and will not affect the secondary alcohol group on the fourth carbon.
5. Step 5: Summarize the products. For Na₂Cr₂O₇/H₂SO₄, the product will be 4-hydroxydecanoic acid (the aldehyde oxidized to a carboxylic acid). For PCC, the product will remain 4-hydroxydecanal as PCC does not oxidize aldehydes or secondary alcohols further.

Key Concepts

Oxidation of Alcohols

Alcohols can undergo oxidation to form carbonyl compounds, such as aldehydes or ketones, depending on the structure of the alcohol and the oxidizing agent used. Primary alcohols typically oxidize to aldehydes, while secondary alcohols oxidize to ketones. Tertiary alcohols do not oxidize easily due to the lack of a hydrogen atom on the carbon bearing the hydroxyl group.

Oxidizing Agents

Different oxidizing agents can yield different products from alcohols. Sodium dichromate (Na2Cr2O7) in acidic conditions is a strong oxidizer that can fully oxidize primary alcohols to carboxylic acids, while pyridinium chlorochromate (PCC) is milder and typically oxidizes primary alcohols to aldehydes without further oxidation to carboxylic acids.

Functional Group Transformation

The transformation of functional groups is a key concept in organic chemistry. In the case of 4-hydroxydecanal, the hydroxyl (-OH) group can be oxidized to a carbonyl group (C=O), resulting in the formation of a ketone or aldehyde, depending on the oxidation conditions. Understanding how functional groups react and change is essential for predicting the products of organic reactions.